The setting is White Sands, NM - an island of gypsum dunes slowly transforming and shifting through the Chihuahuan Desert. The protagonists are three species of small white lizards inhabiting these dunes. The story is recent and rapid evolution: changing ecology, natural selection, and speciation. Our attempt, as field biologists, is to tell that story.
- by Simone Des Roches

24 June 2012

Outreach: White Sands

Good afternoon!Well, it is about time I spoke a bit about our adventures putting on our outreach program last week. On Thursday and Friday we led a "Lizards of the White Sands" day camp for local kids ages seven to fourteen as part of the White Sands Institute (which is an organisation that runs various classes for the public to enjoy the national monument).This year is our second year running the event so fortunately we had a working schedule:

I. Introduction to White Sands, lizard ecology, and evolution.II. Pack up with lots of water, sunscreen, and sunglasses to go out to the dunes.

Isaiah, Mikki, and I before the Natural Selection Game.

III. Natural selection game:I divided the group of kids into 1/3 Roadrunners, or "Predators," and 2/3 Lizards, or "Prey." (on the first day, we had 21 kids - 7 predators, 14 prey; on the second day, we had 12 kids - 4 predators, 8 prey... much more manageable)...

Before the game.

Explaining the rules.

We picked an enclosed interdune where the Lizard-kids were given two dark-painted lizard toys, and one white-painted lizard toy to hide in various locations - under bushes, in the open, and on top of yuccas. I told the kids to make sure they remembered where they set their models. While the Lizard-kids were placing their basking models, the Roadrunners had to turn around and close their eyes (no cheating!).

Ready to let the kids loose for the game.

After the kids had placed all their models, the Roadrunners had less than a minute to gobble up as many lizards they could find (I had to cheat a bit myself and check how many models they had in their hands before calling them back)... i.e. selection.

Now... the tricky part... after the Roadrunner-kids' return, I sent the Lizard-kids to go check and see which lizards survived the feast. I then gave Lizard-kids one lizard toy of the same colour for every one they had left to indicatereproduction and inheritance. After their return, it was again the time for the Roadrunner-kids to feast as another round of selection. We played for only two generations... but I imagine with a greater proportion of prey-to-predators the game could go on for many more (our lizard population depleted pretty rapidly as a result of high predation).

Go Roadrunner-Kids!

To drive home the entire point of the game, I then asked all players- Lizards and Roadrunner-kids to go collect all lizard models that remained in the interdune and pile them up in front of me. I asked all the children how many dark and how many white lizards were out to begin with. On the first day, with 21 kids, we had 14 x 2 = 28 dark lizards and 7 x 1 = 7 white lizards... i.e. the ratio of 2:1 dark:white.

Setting out lizard models.

Laying out the day's catch.

At the end of the game, we had the same number of dark and white lizards - 9 of each. I explained that this is how we think white lizards came to be on White Sands, via natural selection.

Explaining natural selection.

This process takes many generations (where the lizards have babies like themselves), which is why you don't see white lizards taking over rapidly after only one reproduction event - they increase in proportion gradually; over time there are more and more lizards that match the white gypsum substrate of White Sands, or camouflage, and fewer and fewer that stand out.

IV. Catching the three species and learning about their ecology

What were the lizards doing when you first spotted them? What is the shape and colour of each species? How do you tell a male from a female?

Kayla showing her troop a little striped whiptail.

V. Return from the dunes and observe the lizards closer, and if time permits, try noosing some of those lizard toys!

The three funniest comments from the two days? (embarrassingly two came from my mouth):3. (during my introduction talk) Me: "White Sands is very very young compared to the age of the Earth... it is only about 6,000 years old."; Kid: "So it's like a baby?"; Me: "Yes, White Sands is a geological baby"2. (after drawing a horned lizard on a sheet of paper) Kid: "How big are those lizards?"; Me: "Oh about the size of your fist"; Kid: "So... like the size of a hairball... like a cat's hairball?"; Me: "Uh, sure..."1. (when describing ecology in White Sands) Me: "Lots of predators eat lizards... roadrunners, snakes, shrikes, large lizards."; Kid: "Would a coyote eat a lizard?"; Me: "Well, maybe if they were desperate... but lizards are really small compared to coyotes and it may not be worth it for the coyote to chase around such a small meal... it's like if you were to run around after a Cheeto."

Participants showing off their lizard mugs.

We also gave the kids fantastic mugs that our advisor Erica Rosenblum had made featuring my design!

As usual we had a fantastic time with the kids- definitely one of my highlights of the summer. We are certainly fortunate to work in White Sands where we have the opportunity to put on such outreach programs! Thank you to my assistants, Isaiah, Mikki, and Jackie for helping me out this year, to David Bustos and Joan Griggs for doing the logistical work and advertising to get the camp running, and finally to my advisor Bree for letting us take charge and providing the foundation for the program!

Good day for now! Only one catching day left! Stay tuned for a season-recap and some photographic highlights!